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Pulsatile motor output in human finger movements is not dependent on the stretch reflex.

Pulsatile motor output in human finger movements is not dependent on the stretch reflex. 1. Stretch perturbations were delivered during slow voluntary finger movements with the aim of exploring the role of the stretch reflex in generating the 8‐10 Hz discontinuities that characterize these movements. Afferent activity from muscle spindle primary endings in the finger extensor muscles was recorded from the radial nerve, along with the EMG activity of these muscles, and kinematics of the relevant metacarpo‐phalangeal joint. 2. Perturbations elicited a distinct response from the muscle spindles appearing at the recording electrode after 13 ms, and weak reflex responses from the muscle with peak values at 53 and 63 ms during flexion and extension, respectively. 3. The time relations between kinematics, spindle firing and modulations of EMG activity elicited by the perturbations were compared with those of the self‐generated discontinuities. These analyses indicate that stretch reflex mechanisms cannot account for the modulations of EMG activity that give rise to successive 8‐10 Hz discontinuities. 4. A comparison of the reflex responses to perturbations with the EMG modulations during self‐generated movements indicates that the reflex was too weak to account for the pulsatile motor output during voluntary movements. 5. By inference it was concluded that the 8‐10 Hz discontinuities during self‐generated movements are probably generated by mechanisms within the central nervous system. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Physiology Wiley

Pulsatile motor output in human finger movements is not dependent on the stretch reflex.

The Journal of Physiology , Volume 493 (3) – Jun 15, 1996

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References (37)

Publisher
Wiley
Copyright
© 2014 The Physiological Society
ISSN
0022-3751
eISSN
1469-7793
DOI
10.1113/jphysiol.1996.sp021432
Publisher site
See Article on Publisher Site

Abstract

1. Stretch perturbations were delivered during slow voluntary finger movements with the aim of exploring the role of the stretch reflex in generating the 8‐10 Hz discontinuities that characterize these movements. Afferent activity from muscle spindle primary endings in the finger extensor muscles was recorded from the radial nerve, along with the EMG activity of these muscles, and kinematics of the relevant metacarpo‐phalangeal joint. 2. Perturbations elicited a distinct response from the muscle spindles appearing at the recording electrode after 13 ms, and weak reflex responses from the muscle with peak values at 53 and 63 ms during flexion and extension, respectively. 3. The time relations between kinematics, spindle firing and modulations of EMG activity elicited by the perturbations were compared with those of the self‐generated discontinuities. These analyses indicate that stretch reflex mechanisms cannot account for the modulations of EMG activity that give rise to successive 8‐10 Hz discontinuities. 4. A comparison of the reflex responses to perturbations with the EMG modulations during self‐generated movements indicates that the reflex was too weak to account for the pulsatile motor output during voluntary movements. 5. By inference it was concluded that the 8‐10 Hz discontinuities during self‐generated movements are probably generated by mechanisms within the central nervous system.

Journal

The Journal of PhysiologyWiley

Published: Jun 15, 1996

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